1. Technical Field
The present invention relates to an image processing device, a projector, and an image processing method.
2. Related Art
In the case of projecting an image on a projection surface such as a screen to thereby display the image using a projector, there are usually performed a focus adjustment for adjusting the shift of the focus of the image (hereinafter also referred to as a “projection image”) projected on the projection surface, a keystone correction for correcting the distortion (hereinafter also referred to as a “keystone distortion”) of the image range of the projection image, and so on.
As described in, for example, JP-A-2010-32842, the focus adjustment is performed by projecting a patterned image having a stripe shape with white lines and black lines arranged alternately, and varying the focus position of the focusing lens so that the difference in grayscale between the white lines and the black lines of the projection image taken (hereinafter also referred to as a “taken projection image”) is enlarged.
In the case of performing the focus adjustment described above, the focus adjustment becomes insufficient in some cases depending on the projection state of the projector at the beginning of the focus adjustment such as the relative positional relationship between the projector and the projection surface, the defocus condition before the focus adjustment, the focus position of the focusing lens before the focus adjustment, and the performance of the image-taking camera. For example, in the case in which the projector fails to be positioned squarely in front of the projection surface, there might be the case in which the white line portion of the taken projection image becomes dark, the case in which the black line portion of the taken projection image becomes bright, the case in which the taken projection image becomes bright in whole, the case in which the taken projection image becomes dark in whole, and so on. In such cases as described above, since the difference in grayscale between the white line portion and the black line portion of the taken projection image before the adjustment is small from the beginning, there arises a problem that even if the focus position of the focusing lens is varied, the variation is also small to make the accurate adjustment difficult, which might cause the insufficient focus adjustment in some cases. Further, the desired focus position might be located out of the adjustable range.